Multiple lever tool



W. F. TIBBETTS MULTIPLE LEVER TOOL Dec. 4, 1951 2 SHEETSSHEET l FiledNov. 5, 1949 Dec. 4, 1951 w. F. TIBBETTS MULTIPLE LEVER TOOL 2 SHEETS-SHEET 2 Fi'i m Nov. 5, 1949 Mew? Mafia E I m a M U o I $5M... NM] I Il mum h Q W 2 $H fl wm 013a,

EN i

iatented Dec. 4, 19,51

7 Q armres I I M j EMQW Tibhetts, Reading, Mass., assignor to HQKLPonter, Inc Somerville, Mass., at corporation at Massachusetts f'ep n cannmrqnber 5, i9gfier al No.- 125.8 4.

' .16. Claims.

This invention relates to multiple levertools and has a particular application'tetools or the type known as bolt clippers-on-rod-cutters -or severing metal rods. In general -it- -maylae said that the object of the invention isto providea practical construction tor .a hand .operatedotool wherein a uniform force, manually exerted on thehandles-vvi-ll be translated .a variable for-oer at. the jaws, varying. as doestheenesistern e of Ethe. workat the point of. cutting; .lAltlloll li. the. eonstructionmay be. applied .td'tQQls 4 a:

pacities corresponding. to .those.jnow.=.in use, ;.an

important feature is that it permits the genstyuetionof a. tool for cuttin wor the ond su h vani ies.

in ent on l be w ll underswq v-refe in to the o in e crieii n e llusimre embo i e t e of sho bvwav o t-ex: ample n he a p nying erewina where m ri -11s a s e e ati o h i90 F g. 2 is an enlarged section of aportion thereof with parts broken away;

Fig. 3 is an edge view as seen from above in Fig; 2;

4 'is a section. on 'the'line 4-] Qfj'igg "Fig. 5'is a view similar to"Fi g ."2*showingthe partsin open position.

- Inthe'tool illustrated as exemplary or the in;-

position in' Fig. 1 to close the jaWS f'OI' brought:

backtoopen them.

When aro s ve .d' by a tter 0i; ihil fivneg the'edgje's indent and 'plasti'cally deform thegnetal.

As thejaws sink deeper 'and'deeper-intofthe "work the'resistance increasesrapidly. Fir'ral'ly?as the jaws'draw nearthe diameter, exerting a: wedgirrg pressure longitudinally of the rod 'onthesides-pf the indentationptheremaining connecti neck o fmetalbetween them whiehfmayb'e f'-substantia1-' thickness) fails under tension. The

is simply torn apart and if one of the pieces'ishe rea wa v. lever o etii ie he considerable velocity. Asthis occurs the resist-1.:

ance dropssharply.

' I-t w-ilFbenoted that in Fig. 1 of the drawingv showing the tool in closed position the edgessof' 5 the iiaw 16 are shown spaced apartas it. is um necessary and undesirable to. provide. for-move; mer t bringing them into actual contact. because. the work is completed betore they reach such a. position. I

n the conventional boltclipper in common use; a -head such as above described .QPGIEL'tQd-Ebl meansof two bent handle levers, .as shown for example in patent to Lindsay 146,829. These. bent- Ieversforming handles are pivoted inter:

Hi mediate-of their ends to. the jawv tails. and have; short arms connectedto. oneanother adjacent;

the' iaw-tail pivots. These. two arrnsmay-be 1911- sidered as a. toggle .which becomes straighter M the' jaws: are closed. The increase ,inzmechan i 2Q caladvantage of a toggle is-theoreticall infinite but for various reasons the to gle ismoibrwehi close to-dead center position. Thus, while. general themechanical. advantage increasesasithe tool-closes, it is not rproportionali-to the;resistancev of the wor-kand a heavy peakload isencounteredi which taxing on :the operator. .Aiheavy iduty too l'of this type, as presently constructed, having. a nominal capacity for cutting rods 5/ indie. ameter, is 12 inches longand weighs abouttwenty pounds; It is not to be wielded by weaklings. Thisjis aboutthe limit 'for a hand-operated tool (if-this type when weoonsider-that theadvanta-ge of suchatool is-that'it-can be operated byhand andrapi-dly as compared, for example, with any draulical-ly actuated mechanism. The tool herein illustrated-- as an example of my invention is one designed to out rods in diameter. As compared with a rod this represents an increase inload -ofabout 50%,which-could not be practically-handled by existing tools unless'some such means as a winch were utilized for'operating the.

handles Referring now to the drawings and particularly. Figs. 1*and2, the -=toel is operated from two longhandle levers iii-rand =2U-l, pivoted togetherat. their 'distal ends on center a. The jaws maybe carried from the handle levers bymeans: of radius links 22- extending from center-wand joined to the -jaw tails 1'8 onpivots b-. Convenientiyfrom this-same pivot b -extend connecting rods 24' piv oted on-= the center b and having their proximal ends pivoted at center c to 1evers26 whichswingabout fixed centers d on 'the handles. The levers $6 are extended inwardly of; the pivots -d andconneeted to each other by-a-central pivot e. IhiS 6 connection on the pivot e provides for equal and opposite movement of the four bar linkages connecting centers a, b, c, d.

The pair of radius links 22, pair of connecting rods 24 and pair of levers 26 just described are substantially duplicates on opposite sides of the center line, differing slightly when viewed in Fig. 2 because they are right and left hand. It would have been merely prolix and confusing to use different reference numerals but in Fig. 4, where discrimination is helpful, I have added in parentheses to certain numerals the letter Z for those parts associated with handle lever 20-I and the letter 1 for those associated with handle lever 20-r.

in the mechanical construction shown the two handle levers are bifurcated at least at their distal portions and the arms of each lever are brought together and the four arms nested in alternating relation on the pivot a, as best seen in Fig. 4. Similarly, each of the radius links 22 may be double and disposed at either side of the jaw tail at the pivot b. The levers 26 are likewise double and nested at the pivot e and embrace at their outer or distal ends the eyes of eye-bolts '28 forming one end of the connecting rod 24, while the other end of the connecting rod is a bolt 30 having a terminal shackle which, as seen at the right of Fig. 4, embraces the jaw tail l8, and is overlaid by the radius links 22. These two bolts 28 and 30 are of right and left thread and joined by a turnbuckle 32. The operation of this turnbuckle permits the length of the connecting rods to be adjusted to compensate for removal of metal at the jaws IS incidental to resharpening of the tool.

In the example of the invention illustrated a single pivot b connects the jaw tails, the radius links 22, and the connecting rods 24, and this is believed to be the preferable construction. The extent of the movements would be slightly different, but the mechanical arrangement would be substantially the same if two adjacent points of connection were provided, one of the parts being connected directly to the two others and forming a rigid connection between them. For instance, the connecting rod 24 might be connected to link 22 inwardly of pivot b or to the jaw lever I8 distally of that pivot.

The linkages may be covered at the sides of the tool by channel-shaped sheet metal covers 34 fitting over the outside portions of the distal ends of the handles. Their distal ends may be secured by pivot 12 and their flanges may have indented bosses 36 (Fig. 1) at their proximal ends which snap into grooves 38 on the sides of the handles and slide therein when the tool is operated.

I have described the mechanical arrangement shown without any particular attention to its dimensions. .In general the links ab and Cd are not parallel cranks. The design of the parts to permit attainment of the objects of the invention may be effected in accordance with the following principles. Using a chosen jaw lever construction we can, by exerting direct pressure on the backs of the jaws against a piece of work representing the normal load which the tool is to carry, determine the force required for successive increments of jaw movement measured in distances'perpendicular to the center line or in cutting edge angle. These results may be translated mathematically into figures showing the load at the jaw tail for these angles and the corresponding positions of the jaw tail measured 4 perpendicularly to the center. The relation of the load to the travel of the jaw tail may be plotted as a curve and the area under the curve determined for successive increments. On an are representing the travel of the hand grip of the tool, positions may be laid out such that travel of the handle from point to point under a uniform force will give the same increments of work as those for equal jaw tail travel increments. These handle positions may then be .used as a basis for the graphical determination of the dimensions of the links.

The mechanical advantage is varied and the parts are so correlated that the varying resistexerted at the handles.

ance of the work is overcome by a uniform force It should be noted that all the joints are simple pivots that is, rotary joints at a fixed point without any sliding connection which permit a construction of adequate strength and one easily made and freeworking.

'I am aware that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and I therefore desire the present embodiment to be considered in all respects as illustrative and not restrictive, as is in fact clear in several matters from the description itself. Reference is to be had to the appended claims to indicate those principles of the invention exemplified by the particular embodiment described and which I desire to secure by Letters Patent.

I claim:

1. A tool of the class described'comprising in combination a pair of jaw levers and means for swingingly mounting them in opposition to provide a pair of work engaging jaws and a pair of tails, the relative movements of which latter effect opening and closing movements of the jaws, a pair of handles pivoted together, radius links pivotally connected to the jaw tails and handles for supporting the former from the latter, levers pivoted between their ends on the handles remote from the pivotal center of the latter and having inner ends pivotally joined to enforce equal and opposite movement thereof when the handles are moved, and connecting rods extending from points in the levers remote from their pivots on the handles and operatively connected to enforce movement of the joint between the jaw tails and the radius links.

2. A tool of the class described having swinging jaw levers mounted in opposition to provide a pair of work-engaging jaws and a pair of tails and mechanism for operating the jaw tails comprising two four-bar linkages, the elements of a first pair of corresponding links of the two linkages being pivoted together and extended to provide handles, the elements of a second pair of corresponding links being pivoted to the first links and supporting the jaw tails and the elements of a third pair of corresponding links being pivoted to the first links and also being extended and pivoted together to enforce correlated movement of the two linkages when the handles are operated, the elements of a fourth pair of corresponding links connecting the second and third in nonparallel relation, providing on increments of handle grip travel consequent on.

a uniform force exerted thereon effective equal increments of jaw tail travel throughout the major portion of the stroke of the jaws under -load.

3. A tool as defined in claim 2, wherein thewhich constitute the'connection between said driven links and driving links and which are connected thereto by simple pivots, there being also a simple pivot connection between the elements of a pair, all the links forming a system expanding and collapsing symmetrically about the center line on operation'of the handles, the cooperating links] on movement of the handles from point to point under a uniform force enforcing movement of the jaws through proportional distances with varying mechanical advantage corresponding to the varying resistance to indentation of the work.

5. A portable manually operable tool of the multiple lever type for cutting rod comprising a pair of swinging jaw levers having wedgeshaped jaws which indent the work pivoted together at their "distal ends and pairs of intermediate links constituting the means providing for the mutual support between the jaw levers and handles reciprocally and which are connected thereto and to one another by simple pivots, there being also a simple pivot between the elements of a pair, the handles and intermediate links being by such connections integrated in a self-sufficient link system expanding and collapsing symmetrically about the center 'ing to the varying resistance to indentation of the work.

6. A portable manually operable tool of the multiple lever type comprising a pair of swinging jaw levers having wedge-shaped jaws which indent the work and then disrupt it, a pair of operating handles pivoted together at their distal end, a pair of links forming levers of the first class pivoted together at one end and each at an intermediate point to the respective handle levers, connecting links pivoted to the other ends of the lever-forming links and to the jaw levers, and means providing for mutual support between the distal ends of the handles and the jaw levers, the links providing on movement of the handles from point to point under a uniform force enforcing movement of the jaws through proportional distances with varying mechanical advantage corresponding to the varying resistance to indentation of the work.

WILLIS F. TIBBETTS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 806,165 Moore Dec. 5, 1905 1,572,787 Glee et al. Feb. 9, 1926 Certificate of Correction Patent No. 2,577,638

December 4, 1951 WILLIS F. TIBBETTS It is hereby certified that error appears in the printed specification of e above numbered patent requiring correction as follows:

Column 5, line 26, after work insert and then disrupt it, a pair of operating handles;

THOMAS F. MURPHY,

Assistant Uommzlm'oner of Patents. 

